2-phenyl-ethyl-2-(di- and polychlorophenoxy) ethyl sulfides and the method of preparig them



Patented Sept. 21, 1954 UNITED STATEh PATENT OFFICE Z-PHENYL-ETHYL-Z- DI- AN D POLYGHLO Earl W. Glucsenkamp, Dayton, Ohio, assignor to Monsanto Chemical Company, St. Louis, Mo., a corporation of Delaware No Drawing. Application September 28, 1951, Serial No. 248,873

4: Claims. 1 The present invention relates to organic sulfur compounds, more particularly provides a hitherto unknown series of Z-phenylethyl Z-(diand poly-chlorophenoxy)ethy1 sulfides. methods of producing the same, herbicidal compositions containing the new sulfides and methods of destroying undesired plants in which said compositions are employed.

According to the invention there are provided organic sulfides having the formula @omom-s-omomw-Q v 11 in which R, R, R", R' and R are selected from the class consisting of hydrogen and chlorin and in which at least two of R, R, R", 3''

and R. are chlorine. Examples of compounds having the above formula are 2-phenylethy1 2- (pentachlorophenoxy)-ethyl sulfide, Z-phenylethyl 2- (2,3,4,S-tetrachlorophenoxy) ethyl sulfide, Z-phenylethyl 2-(2,3,5 trichlorophenoxy ethyl sulfide, Z-phenylethyl 2-(3,4,5-trichlorophenoxy) ethyl sulfide, 2-phenylethyl 2-(3,4,-dichlorophenoxy) ethyl sulfide, Z-phenylethyl 2-(2,3-dichlorophenoxy) ethyl sulfide, etc.

The present sulfides are readily prepared by contacting a 2- (Z-phenylethyl) mercaptol ethyl chloride or bromide with a phenoxide selected from the class consisting of alkali metal dichlorophenoxides, alkali metal trichlorophenoxides, alkali metal tetrachlorophenoxides, and alkali metal pentachlorophenoxides. Examples of suitable phenoxides are sodium pentachlorophenoxide, potassium 2,3,4,5 tetrachloro-phenoxide, lithium 2,3,5,6 tetrachlorophenoxide, sodium 2,3,4 triohlorophenoxide, sodium 3,4-dichlorophenoxide, potassium 2,3-dichlorophenoxide, etc. The 2- (2-phenylethyl) mercapto] ethyl halides may be obtained by the addition reaction of styrene and 2-mercaptoethanol to yield 2-[(2- phenylethyl)mercaptolethanol and treatment of the latter with hydrogen chloride or hydrogen bromide.

Reaction of the (phenylethyl)mercaptoethyl halides with the dior polychlorophenoxide is effected at ordinary or increased temperatures and in the presence or absence of an inert solvent or diluent. Advantageously the present sulfides are prepared by contacting the halide with the phenoxide in the presence of an unreactive solvent such as ethanol, dioxane, acetone, methyl ethyl ketone, etc., and temperatures of from say,

til

50 C. to the refluxing temperature of the reaction mixture are used. Inasmuch as the reaction involves condensation of one mole of the 2-[ (2-phenylethyl) mercapto] ethyl halide with one mole of the phenoxide, these reactants are advantageously employed in stoichiometric proportions. However, .an excess of either reactant may be employed since any unreacted initial material may be easily recovered from the final product.

The present 2-phenylethyl di or polychlorophenoxyethyl sulfides are well-defined, stable compounds which range from viscous liquids to waxy or crystalline solids. They are particularly valuable as herbicides, but some of this series of compounds also may be advantageously employed as insecticides and pesticides in general, as intermediates in the manufacture of pharmaceuticals, etc.

The invention is further illustrated, but not limited, by the following examples.

Example 1 A mixture consisting of 40 grams (0.2 mole) of 2- E (2-phenylethy1) mercaptol ethyl chloride, 57.? g. (0.2 mole) of sodium pentachlorophenoxide, 1'70 g. of ethanol and 5 cc. of water was refiuxed for six hours, at the end of which time two layers were present in the reaction mixture. The mixture was allowed to stand at ordinary room temperature for several days; then 100 cc. of acetone and an additional 5.7 g. of sodium pentachlorophenoxide was added and refluxing, with stirring, was resumed and continued for another six hours. The solvent was removed by evaporation and the oil which remained allowed to crys tallize. Recrystallization from a mixture of ethanol and acetone gave 64 grams (75% theoretical yield) of the substantially pure Z-phenyl ethyl Z-(pentachlorophenoxy) ethyl sulfide, M. P.

50-52 0., and analyzing as follows:

Oalcd. for Fmmd 0 513 50615 Percent S 6. 9 7. 4 Percent Cl 40. 7 41.2

Example 2 Herbicidal activity of the Z-phenylethyl 2- (pentachlorophenoxy)ethyl sulfide of the preceding example was demonstrated as follows:

A 1% .o'il-in water' emulsion of the sulfide was prepared, employing cyclohexanone as solvent for the sulfide and an emulsifying agent known to the trade as Emulsifier L and comprising a mixture of a polyethylene glycol-derivative-and an alkylbenzenesulfonate. Thisemulsion was further diluted with water to give an emulsion having an 0.3% concentration of the sulfide. The respective emulsions'were applied to the foliage and stems of beanplants having "welldeveloped second leaves, and the treated plants along with similar untreated: plants were placed in a greenhouse for observation. At the end of two weeks plants which had been treated with the 1% and the 0.3% emulsions were found to be completely dead, while the untreated plants, maintained under like conditions of temperature, sunlight and wateringwere in excellent condition.

1 Example 3 Another methodof testing for herbicidal efiiciency of a chemical involves noting the effects on seed germination'an'd plant growth which may be evidenced by spraying soil surfaces. This testing procedure, commonly known as preemergence testing; was conductedas follows.

Boxes having a 5" :x 5" exposed area were partially filled withialayerof .soil, and seeds were. placed .thereonandthen covered with a A" to layer of :soil which had been screened to /4" sieve. Test boxes containing 20 seeds each of rye and cucumber seeds, respectively, were prepared. The surfacesoil of the seeded boxes was then sprayed, respectively, with the "0.3% and 1.0% emulsions of Example 2. The quantity of each emulsion which'was'; applied was calculated to correspond to either 20v lbs. of the sulfide per acre or 50 lbs. of sulfide per acre. The sprayed boxes as well as similarly seeded but unsprayed test boxes were: then maintained at standard conditions oftemperature and watering for a period of two weeks.

"At the end ofthat. timeithexnumber of seedlings in eachaboxwas'counted. 'The number of seedlings in theunsprayed boxes compared to the number'of seedlings'in'thetsprayed boxes was expressed as percent .phytotoxicity.

Therewas evidence from 71% to 100% phytotoxicity to cucumbers at the50 lb./acre concentration and the same .degree'of phytotoxicity to ryeand :cucumber at'both'the 20'lb./acre and the 50 1b./acre concentrations of the sulfide.

The present sulfidesare preferably applied to plants by spraying aqueous emulsions of the same, this-method affording an easy and inexpensive way of destroying plant growth. However, they are likewise effective when applied in dusts, for example, iniadmixture with such carriers as clay, lime, talc, bentonite, pumice, fullers earth, etc.

The present compounds are soluble in the usual organic solvents and may be used in solution, e, g., in kerosene or benzene solution as herbicidal sprays.

Theudispersions or solutions'may be used to destroy alreadyz'existing plant growth by direct application to the undesirable plants, or they may be employed to prevent the plant growth by application to soils. When employed to prevent plant growth, for-example in parking areas, highway a-butments'railway yards, etc, they may be applied either as an aqueous spray or dust or they, maybe admixed with customarily employed temporaryxsurfacing materials, e. g., oils, cinders, etc. "The present invention thus provides a generally useful method of preventing and destroying undesirable plant growth.

What I claim is:

'1. Organic sulfides having the formula RI l 1 in which R R', .Rf',-R"'-and R areselected from the class consisting of :hydrogen and chlorine: and in.which.at' leasttwo of RR, Rl,,--R' and R. are chlorine.

i. .The -method-which comprises refluxing 2- [(2-phenylethyl)mercaptolethyl chloride with sodium .pentachlorophenoxide and recovering 2- phenylethyl Z-(pentachlorophenoxy) ethyl sulfide from theresulting reaction product.

References "Cited in the file of this patent UNITED-STATES PATENTS Number I Name Date 2-,497100 Snyder et a1 -QFeb. 14,1950 2,497,422 Snyder et al. "Feb. 14, 1950 2,567,987 Baumgartner Sept-l8, 1951 2,568,031 Standen et a1 Sept. 18, 1 951 

1. ORGANIC SULFIDES HAVING THE FORMULA
 3. THE METHOD WHICH COMPRISES CONTACTING A HALIDE SELECTED FROM THE GROUP CONSISTING OF 2((2-PHENYLETHYL) MERCAPTO)-ETHYL CHLORIDE AND 2(-PHENYLETHYL) MERCAPTOL) ETHYL BROMIDE WITH A PHENOXIDE SELECTED FROM THE CLASS CONSISTING OF ALKALI METAL DICHLOROPHENOXIDES, ALKALI METAL TRICHLOROPHENOXIDES, ALKALI METAL TETRACHLOROPHENOXIDES AND ALKALI METAL PENTACHLOROPHENOXIDES AND RECOVERING FROM THE RESULTING REACTION PRODUCT SULFIDES HAVING THE FORMULA 